Thaba Nchu is a semi-arid area with low and erratic annual rainfall not exceeding 600mm. Various dryland crops are produced with relatively low yields and high risk of failure. Lack of appropriate technology and other constraints has led to most of the arable land being unused thus restricting agribusiness opportunities in an area where unemployment and food insecurity are thriving. Rainwater harvesting has a huge potential to increase crop yields in Thaba Nchu and reduce the risk of losses, and thus improve food security and enhance sustainability. Different in-field rainwater harvesting (IRWH) techniques have been tested and applied at Glen and Thaba Nchu. This paper gives comparative results for three crops produced with regard to relative profitability and risk of failure. This is done by integrating crop enterprise budgets with crop yield simulations models to calculate per hectare profits over an 81-year period and developing and analyzing cumulative probability functions.